Firearms such a rifles and handguns typically include a trigger assembly by which the user initiates the firing sequence that results in the discharge of the firearm. A trigger assembly configured for use with a bolt-action rifle commonly includes a mechanism for restraining a spring-loaded firing pin that, when released, strikes a primer of an unfired cartridge located in a chamber of the rifle. The impact ignites the primer, which in turn ignites a propellant within the cartridge. The expanding propellant drives a projectile from a casing of the cartridge and through a barrel of the firearm so that the projectile exits the rifle via the muzzle of the barrel.
The trigger assembly restrains the firing pin until the user actuates the trigger assembly by pulling or otherwise exerting pressure on a rotating or linear-motion trigger. Pulling the trigger initiates a series of mechanical interactions within the trigger assembly that result in the release of the firing pin.
The trigger assembly is critical to the safe, reliable, and accurate operation of the rifle. For example, the trigger assembly needs to securely restrain the firing pin so as to minimize the potential for an accidental discharge of the rifle. Configuring the trigger assembly to avoid an accidental discharge, however, can give the trigger assembly undesirable characteristics. The degree of restraint on the firing pin can be increased, and the potential for an accidental discharge decreased, by increasing the friction and the overlap between the various components within the trigger assembly that interact to restrain the firing pin. Increasing the friction and overlap between components, however, can increase the trigger pull weight, i.e., the amount of force that needs to be applied to the trigger; can make the trigger pull rough and uneven; and can increase the distance through which the trigger must be pulled to initiate the firing sequence. These factors can diminish the accuracy and reliability of the rifle; can result in premature wear of the trigger assembly; and can cause fatigue, discomfort, and injury to the user.
Trigger assemblies typically include some type of safety mechanism that further reduces the potential for an accidental discharge when the rifle is not in use. Safety mechanisms usually function by blocking or otherwise interfering with the movement of a single component within the trigger assembly, so that the trigger assembly cannot be actuated. Blocking a single component, however, may be not be sufficient to prevent an accidental discharge, especially when the rifle is dropped or otherwise subjected to some type of impact. On the other hand, a safety mechanism that interferes with the movement of multiple components may be too large, and may require the user to manipulate more than one lever or button to fully engage and disengage the mechanism.
The space allocated for the trigger assembly within a rifle typically is limited, which in turn limits the overall dimensions of the trigger assembly. Also, trigger assemblies are exposed to dirt, carbon, and other contaminants during normal use, and thus need to be cleaned and lubricated on a periodic basis. Trigger assemblies that require significant disassembly to clean and lubricate, or that otherwise are difficult to maintain, often do not receive a proper degree of maintenance.